Three pointers rotate around this dial: one for the Sun one for the Moon the third is for zodiac The Clockwork In the clockwork there are three great co-axial wheels of the same diameter, driven by the same pinion, with 365, 366 and 379 cogs.
The first of these gearing the zodiac and the indicator with the asterisk rotates once a sidereal day.
In fact there were two sun dials on both sides of the location of the Orloj clock and the remains of these on the Old Town Hall walls were visible until 1911 when they were removed.
As the development of clockwork mechanisms progressed, soon clocks could run with more precision than sun dials and were based on the central local sun position. Astronomers then came to worry about time precision by synchronizing the precision of clocks according to star configurations and their movement around the Earth.
Standing under the Orloj at the chime of the hour is not just simply gaping at an old clock. The Apostles come out in a procession - this happens in the top part of the Orloj. Once the windows close, a cockerel flaps and crows in an alcove and then the chimes of the hour can be heard.